Combined Funnel, Concentrator, and Particle Valve Functional Element for Magnetophoretic Bead Transport Based on Engineered Magnetic Domain Patterns

Abstract

AbstractControlled actuation of superparamagnetic beads (SPBs) within a microfluidic environment using tailored dynamic magnetic field landscapes (MFLs) is a potent approach for the realization of point‐of‐care diagnostics within Lab‐on‐a‐chip (LOC) systems. Making use of an engineered magnetic domain pattern as the MFL source, a functional LOC‐element with combined magnetophoretic “funnel”, concentrator, and “valve” functions for micron‐sized SPBs is presented. A parallel‐stripe domain pattern design with periodically decreasing/increasing stripe lengths is fabricated in a topographically flat continuous exchange biased (EB) thin film system by ion bombardment induced magnetic patterning (IBMP). It is demonstrated that, upon application of external magnetic field pulses, a fully reversible concentration of SPBs at the domain pattern's focal point occurs. In addition, it is shown that this functionality may be used as an SPB “funnel”, allowing only a maximum number of particles to pass through the focal point. Adjusting the pulse time length, the focal point can be clogged up for incoming SPBs, resembling an on/off switchable particle “valve”. The observations are supported by quantitative theoretical force considerations.